Advanced magnetic resonance imaging techniques to better understand multiple sclerosis

Abstract

Magnetic resonance imaging (MRI) has considerably improved the diagnosis and monitoring of multiple sclerosis (MS). Conventional MRI such as T₂-weighted and gadolinium-enhanced T₁-weighted sequences detect focal lesions of the white matter, damage of the blood-brain barrier, and tissue loss and inflammatory activity within lesions. However, these conventional MRI metrics lack the specificity required for characterizing the underlying pathophysiology, especially diffuse damage occurring throughout the whole central nervous system. To overcome these limitations, advanced MRI techniques have been developed to get more sensitive and specific parameters of focal and diffuse brain damage. Among these techniques, magnetization transfer imaging, diffusion MRI, functional MRI, and magnetic resonance spectroscopy are the most significant. In this article, we provide an overview of these advanced MRI techniques and their contribution to the better characterization and understanding of MS.

Keywords: Diffusion MRI; Functional MRI; MR spectroscopy; MRI; Magnetization transfer imaging; Multiple sclerosis.

Fig. 1

Conventional T₂-weighted (a) and T₁-weighted post-gadolinium (b) images from a patient with early MS. Arrow indicates an acute inflammatory demyelinating lesion

Fig. 2

MTR map from a patient with early MS. Note that the MS lesion (arrow) presents a very low signal demonstrating a low MTR value

Fig. 3

Diffusion imaging including ADC map (a), FA map (b), and diffusion tensor tracking image (c) from a patient with early MS. Note that the MS lesion (arrow) presents abnormal diffusion contrasts compared to normal appearing tissue

Fig. 4

Functional imaging from a relapsing-remitting MS patient showing activations of primary and supplementary motor areas and sensoricortex during a hand motor task

Fig. 5

Spectra representing the metabolic patterns in a focal inflammatory demyelinating lesion (a) and in a focal demyelinating lesion without inflammation (b)

Fig. 6

Susceptibility-weighted image acquired at 3T on a patient with early MS. Note the significant change of contrast in the MS lesion (arrow)